Hall sensor - magnet geometry for large stroke linear position sensing

ABSTRACT

Position sensing units, comprising a magnetic assembly (MA) having a width W measured along a first direction and a height H measured along a second direction and including at least three magnets having respective magnetic polarizations that define along the first direction at least a left MA domain, a middle MA domain and a right MA domain, wherein the magnetic polarizations of each MA domain are different, and a magnetic flux measuring device (MFMD) for measuring a magnetic flux B, wherein the MA moves relative to the MFMD along the first direction within a stroke L that fulfils 1 mm≤L≤100 mm, stroke L beginning at a first point x 0  and ending at a final point x max , and wherein a minimum value D min  of an orthogonal distance D, measured along the second direction between a particular MA domain and the MFMD, fulfills L/D min &gt;10.

CROSS REFERENCE TO EXISTING APPLICATIONS

This application is a 371 of international patent applicationPCT/IB2021/056693 filed Jul. 26, 2021 and claims priority from U.S.Provisional Patent Application No. 63/059,200 filed Jul. 31, 2020, whichis incorporated herein by reference in its entirety.

FIELD

Embodiments disclosed herein relate in general to position sensingunits, and in particular to position sensing in compact digital camerasincluded in mobile electronic devices.

BACKGROUND

Many compact digital cameras that are integrated in handheld electronicdevices (“devices”) such as smartphones or tablets use actuators such asvoice coil motors (VCMs) or stepper motors, e.g. for actuating a cameralens along a trajectory having a particular direction and range(“stroke” or “L”). The actuation is controlled by a position sensingunit, which is typically based on a magnet assembly (“MA”) that movesrelative to a magnetic flux measuring device (MFMD) for example a Hallsensor. For stable control, the position sensing unit must support twoconditions: a) it must exhibit linear behavior, i.e. its slope S=AB/Axmust be constant along the entire stroke (“linear range”), where AB isthe change in magnetic flux density between two points located at adistance Δx from each other. For example, the linear range of theposition sensing unit limits the stroke, and b) the slope S=AB/Ax withinthe linear range must be sufficiently steep, i.e. it must be above acertain threshold, e.g. S>50 mT or S>200 mT.

FIG. 1A shows a first known example of a position sensing unit 100comprising a magnet assembly (“MA”) 102. MA 102 includes two rectangularmagnets with a polarizations 104, the MA having a width W102 and a MAcenter “C” (with respect to the x direction or just “with respect tox”)) located at the symmetry axis (“SA”) 109 (with respect to the ydirection or just “with respect to y”) of MA 102, and a MFMD 106. MA 102causes a magnetic field 108 in its surroundings. MFMD 106 is located ata constant distance D=D_(C) (measured along the y axis) from MA 102,which may be D_(C)=0.1 mm-2 mm. For position sensing, MA 102 moves alonga substantially straight line in the x direction and relative to MFMD106. The position of MA 102 along the straight line (“x”) changes when xvaries from x₀ to x_(max) (this being the “stroke”). That is, MA moveswithin the stroke only. D is substantially constant between x₀ andx_(max), i.e. D is not a function of x. In graph 107, the magnetic fluxdensity (“B”) measured by MFMD 106 is shown versus the x position of MA102. B is a function of x, i.e. B=B(x). Within stroke L ranging from x₀to x_(max), slope S=(B_(max)−B₀)/L of B is linear. In some examples,W102 may be 0.6 mm-10 mm, L may be 0.5 mm-1 mm. In a typical example forfocusing a camera lens, D=200 μm and L=700 μm, so that a ratio of L andD is L/D=3.5. For many actuator sensing examples, S is sufficientlysteep. However, L/D is relatively small.

FIG. 1B shows a second known example of a position sensing unit 110comprising a MA 112 that includes a single rectangular magnet having apolarization 114 and a width W112, and a MFMD 116. MA 112 causes amagnetic field 118. MFMD 116 is located at a distance D away from MA102. Similar to the shown in FIG. 1A, a magnet center “C” (with respectto the x direction) is located at a SA 119 (with respect to the ydirection) of MA 202. For position sensing, MA 112 moves along asubstantially straight line in the x direction relative to MFMD 116. Dis substantially constant between x₀ and x_(max). In graph 117, themagnetic flux density B measured by MFMD 116 is shown versus the xposition of MA 112. Slope S=(B_(max)− B₀)/L of B is linear in a range L.L/D can be relatively large. However, for most actuator sensingscenarios, S is not sufficiently steep. Therefore, this design is hardlyused in today's devices.

Novel Telephoto “(Tele”) cameras entering the market have largeeffective focal lengths (EFL) of e.g. 10 mm-40 mm for large zoom factorsand for Macro photography with high object-to-image magnifications ofe.g. 1:1-15:1 at object-lens distances (“u”) of 5 cm-15 cm. Focusingsuch a large EFL camera to a short u as small as 5 cm-15 cm requireslarge lens strokes significantly exceeding 1 mm.

Using the thin lens equation 1/EFL=1/u+1/v (“v” being the lens-imagedistance) and a Tele camera having EFL=25 mm as an example, a lensstroke of about 6.3 mm is required to focus to 10 cm (with respect tofocus on infinity). Controlling such large lens strokes cannot besupported by position sensing units used at present in the compactcamera industry. Further examples that require large strokes ofcomponents are, for example, (i) a 2-state zoom camera described inco-owned international patent application PCT/IB2020/051405, (ii) a popout mechanism that collapses a camera's total track length (TTL) such asdescribed in the co-owned international patent applicationPCT/IB2020/058697 and (iii) a continuous zoom camera such as describedin co-owned U.S. provisional patent application No. 63/119,853 filed 1Dec. 2020.

There is need for, and it would be beneficial to have a position sensingunit with a compact form factor that allows realizing position sensingwith along large strokes L and with sufficiently large slope S.

SUMMARY

1. In various embodiments, there are provided position sensing units,comprising: a magnetic assembly (MA) having a width W measured along afirst direction and a height H measured along a second direction andincluding at least three magnets having respective magneticpolarizations that define along the first direction at least a left MAdomain, a middle MA domain and a right MA domain, wherein the magneticpolarizations of each MA domain are different; and a magnetic fluxmeasuring device (MFMD) for measuring a magnetic flux B, wherein the MAis configured to move relative to the MFMD along the first directionwithin a stroke L that fulfils 1 mm≤L≤100 mm, stroke L beginning at afirst point x₀ and ending at a final point x_(max), and wherein aminimum value D_(min) of an orthogonal distance D measured along thesecond direction between a particular MA domain of the MA and the MFMDof the position sensing unit, fulfills L/D_(min)>10. The magnets may bemade from a Neodymium based material.

In some embodiments, the MA has a symmetry axis parallel to the seconddirection. In some embodiments, the symmetry axis is located at a centerof the middle MA domain.

In some embodiments, D is not constant for different positions withinstroke L.

In some embodiments, L/D_(min)>15. In some embodiments, L/D_(min)>20.

In some embodiments, B at x₀ is B₀ and B at x_(max) is B_(max), and aslope S=(B₀−B_(max))/L is larger than 10 mT/mm. In some embodiments, Sis larger than 100 mT/mm. In some embodiments, S is larger than 1000mT/mm. In some embodiments, S is larger than 2500 mT/mm.

In some embodiments, the magnetic polarization of the left MA domain isdirected towards the MFMD.

In some embodiments, the magnetic polarization of the right MA domain isdirected away from the MFMD.

In some embodiments, the magnetic polarization of the middle MA domainis directed parallel or anti-parallel to the first direction.

In some embodiments, a position sensing unit as above or below may beincluded in a voice coil motor (VCM). In some embodiments, the VCMincludes four coils. In some embodiments, the VCM is included insmartphone camera.

In some embodiments, the MFMD is a Hall sensor.

In some embodiments, a value of D between the left MA domain and MFMD isD(x₀), wherein a value of D between the right MA domain and the MFMD isD(x_(max)), wherein a value of D between the middle MA domain and theMFMD is D(x_(max/2)) and wherein D(x₀)≤D(x_(max/2)) andD(x_(max))≤D(x_(max/2)). In some embodiments, a value of D between themiddle MA domain and the MFMD is D(x_(max/2)) and whereinD(x₀)=D(x_(max))≤D(x_(max/2)).

In some embodiments, the left, middle and right MA domains arerectangular. In some embodiments, the left and right MA domains aretrapezoids, and the middle MA domain is a convex pentagon. In someembodiments, the left and right MA domains are trapezoids, and themiddle MA domain is a concave pentagon.

In some embodiments, the MA additionally includes a fourth MA domain anda fifth MA domain having respective magnetic polarizations, wherein thefourth MA domain is located to the left of the left MA domain andwherein the fifth MA domain is located to the right of the right MAdomain. In some embodiments, the magnetic polarization of the fourth MAdomain is directed away from the MFMD. In some embodiments, the magneticpolarization of the fifth MA domain is directed towards the MFMD.

In some embodiments, L<20 mm. In some embodiments, L<10 mm. In someembodiments, L<7.5 mm. In some embodiments, L<5 mm.

In some embodiments, L/W>0.5. In some embodiments, L/W>0.75.

In some embodiments, L/H>3. In some embodiments, L/H>5.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting examples of embodiments disclosed herein are describedbelow with reference to figures attached hereto that are listedfollowing this paragraph. The drawings and descriptions are meant toilluminate and clarify embodiments disclosed herein, and should not beconsidered limiting in any way. Like elements in different drawings maybe indicated like numerals.

FIG. 1A shows a first known example of a position sensing unit;

FIG. 1B shows a second known example of a position sensing unit;

FIG. 2A shows in cross-section an embodiment of a position sensing unitdisclosed herein;

FIG. 2B shows a magnetic field distribution of a MA in the positionsensing unit of FIG. 2A;

FIG. 2C shows the magnetic field density sensed by a MFMD in theposition sensing unit of FIG. 2A;

FIG. 3 shows in cross-section another embodiment of a position sensingunit disclosed herein;

FIG. 4 shows in cross-section yet another embodiment of a positionsensing unit disclosed herein;

FIG. 5A shows in cross-section yet another embodiment of a positionsensing unit disclosed herein;

FIG. 5B shows an embodiment of a voice coil motor (“VCM”) disclosedherein.

DETAILED DESCRIPTION

FIG. 2A shows an embodiment of a position sensing unit disclosed hereinand numbered 200, comprising a magnet assembly 202 and a magnetic fluxmeasuring device 206. Graph 207 shows B measured by MFMD 106 versus thex position of MA 102. FIG. 2B shows a magnetic field distribution 210 ofMA 202. Box 212 indicates a y position within stroke L where a magneticflux density 214 as shown in FIG. 2C is sensed by MFMD 206.

MA 202 includes three rectangular permanent magnets 202 a, 202 b and 202c having respective magnetic polarizations 204 a, 204 b and 204 c.Magnets 202 a and 202 c are identical in shape and dimensions, butopposite respective magnetizations 204 a and 204 c. Magnets 202 a and202 c are positioned symmetrically with respect to magnet 202 b, i.e.both magnets 202 a and 202 c are (i) located at a same distance d202from magnet 202 b and (ii) are positioned at a same relative ycoordinate ΔH with respect to magnet 202 b. A center “C” of MA 202 islocated at symmetry axis SA 209 of both magnet 202 b and MA 202. MA 202is shaped symmetrically around C with respect to y. MA 202 has a widthW202 and a height H202.

Magnets described herein may be made from any material known to be usedin the industry, specifically in digital cameras used in mobileelectronic devices such as smartphones, for example any Neodymium basedmaterial, e.g. N48H, N48SH etc. x₀ and x_(max) may be chosen so thattheir middle or symmetry point x_(S)=x_(max/2) is located at C, or theymay be chosen otherwise. That is, the symmetry axis of the stroke withrespect to y is located at x_(S)=x_(max)/2 and may be identical with theSA 209 of MA 202 located at C (such as shown in FIG. 2A) or it may belocated at another position.

The orthogonal distance between any component included in MA 202 andMFMD 206 is marked “D”. “Orthogonal distance” means that it representsonly the y-component of a distance between any component included in MA202 and MFMD 206. Values of D at points x₀, C and x_(max) are markedrespectively D(x₀), D_(C) and D(x_(max)). At x₀ and x_(max), D has aminimal value D_(min).

As an example, D between magnet 202 a and MFMD 206 is D(x₀) and Dbetween magnet 202 b and MFMD 206 is D_(C), irrespective from the actualrelative distance between magnet 202 a and 202 b respectively and MFMD206. As to the relative motion of MA 202 and MFMD 206, in general anactual relative distance is composed of a distance component measuredalong x and a distance component measured along y. It is noted here thatD refers to a distance between a magnet and a packaging device thatincludes a MFMD, and not to the distance the MFMD itself. In general, aMFMD is included in a packaging device having a housing, wherein theMFMD is located at a MFMD-housing distance of about 50 μm-250 μm fromthe housing. For calculating the distance between a magnet and the MFMD,the MFMD-housing distance must be added to D. Additionally, it is notedthat D is not shown in scale.

In all examples shown herein, D(x₀) and D(x_(max)) can be smaller thanor equal to D(x) fulfilling D(x₀), D(x_(max))≤D(x). The closest distancebetween one of the magnets and the MFMD D_(min)=D(x₀)=D_(max). That is,D(x₀) and D(x_(max)) are smaller than or equal to all other distances inthat range. In position sensing unit 200, D(x₀)=D(x_(max))<D_(C) andL/D_(min)>10. Typically, D_(min)≥0.1 mm.

At x₀, magnetic polarization 204 a is directed substantially towardsMFMD 206. At x_(max), magnetic polarization 204 c is directedsubstantially away from MFMD 206. At C, magnetic polarization 204 b isdirected substantially in parallel or anti-parallel to X. Magnets 202 a,202 b and 202 c define three MA domains, a left, a middle and a right MAdomain respectively, wherein the magnet polarizations of each MA domainare different from each other.

Magnetic flux density B is a function of x, i.e. B=B(x). In L, the slopeS=(B_(max)−B₀)/Δx of B is linear. In all following examples, S is givenfor an ideally linear slope such as 216 (see FIG. 2C) which has a samestarting point (x₀, B₀) and a same end point (x_(max), B_(max)) as anactual slope 214 (see FIG. 2C). Values of S are given at D_(C).

As mentioned, graph 207 in FIG. 2C shows magnetic flux densities versusx, so it is a “B vs. x curve”. Actual magnetic flux density slope 214 issensed along the coordinates indicated by the arrow L in FIG. 2A. Ideal(linear) magnetic flux density slope 216 is shown for comparison.Clearly, actual magnetic flux density slope 214 deviates from idealmagnetic flux density slope 216.

FIG. 3 shows another embodiment of a position sensing unit disclosedherein and numbered 300. Unit 300 comprises a MA 302 that includes threepermanent magnets 302 a, 302 b and 302 c having respective magneticpolarizations 304 a, 304 b and 304 c, and a MFMD 306. Magnets 302 a, 302b and 302 c are not rectangular. Magnets 302 a and 302 c have identicalshape and dimensions, but opposite magnetization 304 a and 304 c.Magnets 302 a and 302 c are positioned symmetrically with respect to 302b, i.e. both 302 a and 302 c are (i) located at a same distance d302from 302 b and (ii) are positioned at a same relative y coordinate ΔH302with respect to 302 b. Center C of MA 302 (with respect to x) is locatedat the SA 309 (with respect to y) of both magnet 302 b and MA 302. MA302 is shaped symmetrically around C with respect to y.

MA 302 causes a magnetic field (not shown). At C, MFMD 306 is located atD_(C) away from MA 302. MA 302 moves along a stroke in x directionrelative to MFMD 306. The position of MA 302 along x varies from x₀ tox_(max). x₀ and x_(max) may be chosen so that their middle or symmetrypoint x_(s)=x_(max/2) is located at C, or they may be chosen otherwise.It is noted that D is not shown in scale.

Between x₀ and x_(max), orthogonal distance D is a function of x,D=D(x). For 300, D(x₀)=D(x_(max))≤D_(C), D(x₀)=D(x_(max))=D_(min) andL/D_(min)>10. Typically, D_(min)≥0.1 mm. For the purpose of illustratingthe definition of D, D is shown at 2 further, arbitrary positions x₁ andx₂, where D is given by D(x₁) and D(x₂) respectively. At x₀, magneticpolarization 304 a is substantially directed towards MFMD 306. Atx_(max), 304 c is substantially directed away from MFMD 306. At C, 304 bis directed substantially parallel or anti-parallel to x. Magnets 302 a,302 b and 302 c define three MA domains, a left, a middle and a right MAdomain respectively, wherein the magnet polarizations of each MA domainare different from each other.

B 309 measured by MFMD 306 is shown versus the x position of MA 202 (“Bversus x curve”). B is a function of x, i.e. B=B(x). In L,S=(B_(max)−B₀)/Δx of B is linear. Example values of given in Table 1.Values of S are given at D_(C). An advantage of MA 302 over MA 202 isthat a B versus x curve within L exhibits a higher linearity. That is,the B vs. x curve of MA 302 varies less from an ideal linear shape suchas 216 than the B vs. x curve of MA 202.

TABLE 1 Value Unit W302 8 mm H302 See HL302a W302a 2.2 mm HL302a 0.9HR302a 0.55 W302b 2.7 H302b 0.6 d302 0.45 ΔH302b 0.1 S  10-6000 mT/mm,at D_(C). L 7.5 mm D_(C) 0.2-1   mm D_(min) 0.1-0.7 mm L/W302 0.94L/H302 8.33 HL302a/HR302a 1.64 H302b/ΔH302b 6 L/D_(min) 10.7-75  

FIG. 4 shows yet another embodiment of a position sensing unit disclosedherein and numbered 400. Unit 400 comprises a MA 402 that includes threenon-rectangular permanent magnets 402 a, 402 b and 402 c havingrespective magnetic polarization 404 a, 404 b and 404 c, and a MFMD 406.Magnets 402 a and 402 c have the same shape and dimensions, but oppositemagnetizations 404 a and 404 c. Magnets 402 a and 402 c are positionedsymmetrically with respect to 402 b, i.e. both 402 a and 402 c are (i)located at a same distance d402 from 402 b and (ii) are positioned at asame relative Y coordinate ΔH402 with respect to 402 b. Center C of MA402 (with respect to x) is located at the SA 409 (with respect to y) ofboth magnet 402 b and MA 402. MA 402 is shaped symmetrically around Cwith respect to y.

MA 402 causes a magnetic field (not shown). At C, MFMD 406 is located atD_(C) away from MA 402. MA 402 moves along a stroke in x directionrelative to MFMD 406. The position of MA 402 along x varies from x₀ tox_(max). x₀ and x_(max) may be chosen so that their middle or symmetrypoint x_(s)=x_(max/2) is located at C, or they may be chosen otherwise.

Between x₀ to x_(max), orthogonal distance D is a function of x, D=D(x).For 400, D(x₀)=D(x_(max))≤D_(C), D(x₀)=D(x_(max))=D_(min) andL/D_(min)>10. Typically, D_(min)≥0.1 mm. At x₀, the magneticpolarization 404 a is substantially directed towards MFMD 406. Atx_(max), 404 c is substantially directed away from MFMD 406. At C, 404 bis directed substantially parallel or anti-parallel to X. Magnets 402 a,402 b and 402 c define three MA domains, a left, a middle and a right MAdomain respectively, wherein the magnet polarizations of each MA domainare different from each other. It is noted that D is not shown in scale.

B 409 measured by MFMD 406 is shown versus the x position of MA 202. Bis a function of x, i.e. B=B(x). In L, S=(B_(max)−B₀)/ΔX of B is linear.Example values of position sensing unit 400 are given in Table 2. Valuesof S are given at D_(C). An advantage of MA 402 over MA 202 is that a Bversus x curve within L exhibits a higher linearity.

TABLE 2 Value Unit W402 5.35 H402 See HL402a W402a 1.55 HL402a 0.8HR402a 0.55 WR402a 0.625 W402b 1.2 H402b 0.55 d402 0.525 ΔH402b 0.05 S 10-6000 mT/mm, at D_(C). L 5 mm D_(min) 0.1-0.5 mm D_(C) 0.2-1   mmL/W402 0.93 L/H402 6.25 HL402a/HR402a 1.45 H402b/ΔH402b 11 L/D_(min)10.0-50  

FIG. 5A shows yet another embodiment of a position sensing unitdisclosed herein and numbered 500. Unit 500 comprises a MA 502 thatincludes five permanent magnets 502 a, 502 b, 502 c, 502 d and 502 ehaving respective magnetic polarizations 504 a, 504 b, 504 c, 504 d and504 e, and a MFMD 506. Magnets 502 a, 502 b and 502 c are notrectangular, while magnets 502 d and 502 e are rectangular. Magnets 502a and 502 c as well as 502 d and 502 e have the same shape anddimensions, but opposite magnetizations 504 a and 504 c and 504 d and504 e respectively. Magnets 502 a, 502 c, 502 d and 502 e are positionedsymmetrically with respect to magnet 502 b. A magnet sub-assemblyincluding magnets 502 a, 502 b and 502 c is identical with MA 302 shownin FIG. 3 . Center C of MA 502 (with respect to x) is located at the SA509 (with respect to y) of both magnet 502 b and MA 502. MA 502 isshaped symmetrically around C with respect to y.

MA 502 causes a magnetic field (not shown). At C, MFMD 506 is located atD_(C) away from MA 502. MA 502 moves along a stroke in x directionrelative to MFMD 506. The position of MA 502 along x varies from x₀ tox_(max). x₀ and x_(max) may be chosen so that their middle or symmetrypoint x_(s)=x_(max/2) is located at C, or they may be chosen otherwise.

Between x₀ to x_(max), orthogonal distance D is a function of x, D=D(x).For 500, D(x₀)=D(x_(max))≤D_(C), D(x₀)=D(x_(max))=D_(min) andL/D_(min)>10. Typically, D_(min)≥0.1 mm. At x₀, the magneticpolarization 504 a is substantially directed towards MFMD 506. Atx_(max), 504 c is substantially directed away from MFMD 506. At C, 504 bis directed substantially parallel or anti-parallel to X. 504 d isdirected substantially anti-parallel to 504 a. 504 e is directedsubstantially anti-parallel to 504 c. Additionally to the three MAdomains defined by magnets 502 a, 502 b and 502 c, in MA 502 there aretwo additional MA domains defined by magnets 502 d and 502 e.

B (not shown) is measured by MFMD 506 versus the x position of MA 202. Bis a function of x, i.e. B=B(x). In L, S=(B_(max)−B₀)/ΔX of B is linear.Example values of given in Table 3. For the values of magnetsub-assembly including magnets 502 a, 502 b and 502 c see magnets 302 a,302 b and 302 c of Table 1 respectively. Values of S are given at D_(C).

An advantage of MA 502 over MA 302 is that a B versus x curve has ahigher linearity for the same dimensions of magnets 502 a, 502 b and 502c (which have the same dimensions as magnets 302 a, 302 b and 302 c).

TABLE 3 Value Unit W502 19.2 mm H502 See H502d mm W502d, W502e 2.55 mmH502d, H502e 0.9 mm S  10-6000 mT/mm, at D_(C). L 13.4 mm D_(min)0.1-1   mm D_(C) 0.2-0.9 mm L/W502 0.70 L/H502 14.89 L/D_(min) 13.4-134 

FIG. 5B shows an embodiment of a voice coil motor (“VCM”) disclosedherein and numbered 510. VCM 510 includes a coil assembly (“CA”) 520 andposition sensing unit 500. CA 520 includes four coils 520 a, 520 b, 520c and 520 d and can generate a magnetic field.

In VCM 510, the magnetic field caused by position sensing unit 500additionally provides, together with the magnetic field generated by CA520, the magnetic field configuration which is required for actuating arelative motion between MA 502 and CA 520 as well as MFMD 506. Typicallyand with respect to a device that includes VCM 510, MFMD 506 and CA 520are at rest and MA 502 moves. In some examples for lens focusing indevices that include a camera, MA 502 may be fixedly coupled to thecamera's lens for actuating the lens with respect to camera's imagesensor which is at rest with respect to the device. An advantage of MA502 over MA 302 is that it allows a faster VCM actuation.

In other embodiments, a VCM like VCM 510 may include position sensingunit 200, 300 or 400.

While this disclosure has been described in terms of certain embodimentsand generally associated methods, alterations and permutations of theembodiments and methods will be apparent to those skilled in the art.The disclosure is to be understood as not limited by the specificembodiments described herein, but only by the scope of the appendedclaims.

Unless otherwise stated, the use of the expression “and/or” between thelast two members of a list of options for selection indicates that aselection of one or more of the listed options is appropriate and may bemade.

It should be understood that where the claims or specification refer to“a” or “an” element, such reference is not to be construed as therebeing only one of that element.

Furthermore, for the sake of clarity the term “substantially” is usedherein to imply the possibility of variations in values within anacceptable range. According to one example, the term “substantially”used herein should be interpreted to imply possible variation of up to10% over or under any specified value. According to another example, theterm “substantially” used herein should be interpreted to imply possiblevariation of up to 5% over or under any specified value. According to afurther example, the term “substantially” used herein should beinterpreted to imply possible variation of up to 2.5% over or under anyspecified value.

All references mentioned in this specification are herein incorporatedin their entirety by reference into the specification, to the sameextent as if each individual reference was specifically and individuallyindicated to be incorporated herein by reference. In addition, citationor identification of any reference in this application shall not beconstrued as an admission that such reference is available as prior artto the present invention.

1. A position sensing unit, comprising: a) a magnetic assembly (MA)having a width W measured along a first direction and a height Hmeasured along a second direction and including at least three magnetshaving respective magnetic polarizations that define along the firstdirection at least a left MA domain, a middle MA domain and a right MAdomain, wherein the magnetic polarizations of each MA domain aredifferent; and b) a magnetic flux measuring device (MFMD) for measuringa magnetic flux B, wherein the MA is configured to move relative to theMFMD along the first direction within a stroke L that fulfils 1 mm≤L≤100mm, stroke L beginning at a first point x₀ and ending at a final pointx_(max), and wherein a minimum value D_(min) of an orthogonal distance Dmeasured along the second direction between a particular MA domain andthe MFMD of the position sensing unit, fulfills L/D_(min)>10.
 2. Theposition sensing unit of claim 1, wherein the MA has a symmetry axisparallel to the second direction.
 3. The position sensing unit of claim1, wherein D is not constant for different positions within stroke L. 4.The position sensing unit of claim 1, wherein L/D_(min)>15.
 5. Theposition sensing unit of claim 1, wherein L/D_(min)>20.
 6. The positionsensing unit of claim 1, wherein B at x₀ is B₀ and B at x_(max) isB_(max) and wherein a slope S=(B₀−B_(max))/L is larger than 10 mT/mm. 7.The position sensing unit of claim 1, wherein B at x₀ is B₀ and B atx_(max) is B_(max) and wherein a slope S=(B₀−B_(max))/L is larger than100 mT/mm.
 8. The position sensing unit of claim 1, wherein B at x₀ isB₀ and B at x_(max) is B_(max) and wherein a slope S=(B₀−B_(max))/L islarger than 1000 mT/mm.
 9. The position sensing unit of claim 1, whereinB at x₀ is B₀ and B at x_(max) is B_(max) and wherein a slopeS=(B₀−B_(max))/L is larger than 2500 mT/mm.
 10. The position sensingunit of claim 1, wherein the magnetic polarization of the left MA domainis directed towards the MFMD.
 11. The position sensing unit of claim 1,wherein the magnetic polarization of the right MA domain is directedaway from the MFMD.
 12. The position sensing unit of claim 1, whereinthe magnetic polarization of the middle MA domain is directed parallelor anti-parallel to the first direction.
 13. The position sensing unitof claim 1, included in a voice coil motor (VCM).
 14. The positionsensing unit of claim 1, wherein the MFMD is a Hall sensor.
 15. Theposition sensing unit of claim 2, wherein the symmetry axis is locatedat a center of the middle MA domain.
 16. The position sensing unit ofclaim 3, wherein a value of D between the left MA domain and MFMD isD(x₀), wherein a value of D between the right MA domain and the MFMD isD(x_(max)), wherein a value of D between the middle MA domain and theMFMD is D(x_(max/2)) and wherein D(x₀)≤D(x_(max/2)) andD(x_(max))≤D(x_(max/2)).
 17. The position sensing unit of claim 3,wherein a value of D between the left MA domain and MFMD is D(x₀),wherein a value of D between the right MA domain and the MFMD isD(x_(max)), wherein a value of D between the middle MA domain and theMFMD is D(x_(max/2)) and wherein D(x₀)=D(x_(max))≤D(x_(max/2)).
 18. Theposition sensing unit of claim 1, wherein the left, middle and right MAdomains are rectangular.
 19. The position sensing unit of claim 1,wherein the left and right MA domains are trapezoids, and the middle MAdomain is a convex pentagon.
 20. The position sensing unit of claim 1,wherein the left and right MA domains are trapezoids, and the middle MAdomain is a concave pentagon.
 21. The position sensing unit of claim 13,wherein the VCM includes four coils.
 22. The position sensing unit ofclaim 13, wherein the VCM is included in smartphone camera.
 23. Theposition sensing unit of claim 1, wherein the MA additionally includes afourth MA domain and a fifth MA domain having respective magneticpolarizations, wherein the fourth MA domain is located to the left ofthe left MA domain and wherein the fifth MA domain is located to theright of the right MA domain.
 24. The position sensing unit of claim 23,wherein the magnetic polarization of the fourth MA domain is directedaway from the MFMD.
 25. The position sensing unit of claim 23, whereinthe magnetic polarization of the fifth MA domain is directed towards theMFMD.
 26. The position sensing unit of claim 1, wherein L<20 mm.
 27. Theposition sensing unit of claim 1, wherein L<10 mm.
 28. The positionsensing unit of claim 1, wherein L<7.5 mm.
 29. The position sensing unitof claim 1, wherein L<5 mm.
 30. The position sensing unit of claim 1,wherein L/W>0.5.
 31. The position sensing unit of claim 1, whereinL/W>0.75.
 32. The position sensing unit of claim 1, wherein L/H>3. 33.The position sensing unit of claim 1, wherein L/H>5.
 34. The positionsensing unit of claim 1, wherein the at least three magnets are madefrom a Neodymium based material.